[Expression of microRNA-155 and regulative T cell in sepsis patients and their relationship]

To investigate the adjustment effect of microRNA-155 on CD4(+)CD25(+) regulative T cell (Treg) in peripheral blood of sepsis patients, and to elucidate the role of miR-155 in the pathogenesis of sepsis.

A retrospective study was conducted. 60 sepsis patients (mild n=20, moderate n=20, and severe n=20) from emergency room or intensive care unit (ICU) of the Fourth Hospital of Jiangsu University were enrolled. 20 healthy volunteers were enrolled as controls. Real-time fluorescent quantitation polymerase chain reaction (qRT-PCR) was used to detect the levels of miR-155 and Foxp3 mRNA expressions in peripheral blood. CD4(+)CD25(+) Treg cells in peripheral blood were identified by flow cytometry. Peripheral interleukin-10 (IL-10) was measured by enzyme-linked immunosorbent assay (ELISA).

The expressions of miR-155, Treg, Foxp3 mRNA and the level of IL-10 were higher in the patients with sepsis than those in healthy control group [Treg: (2.89±1.13)% vs. (2.32±0.91)%, t=10.540, P=0.002; miR-155: 1.19±0.48 vs. 0.80±0.33, t=8.605, P=0.006; Foxp3 mRNA: 0.18±0.08 vs. 0.13±0.03, t=6.862, P=0.008; IL-10: 56.89±17.28 ng/L vs. 33.24±11.93 ng/L, t=12.742, P=0.001]. These variables were elevated gradually with the elevation of acute physiology and chronic health evaluation II (APACHEII) score. The expressions of Treg, miR-155, Foxp3 mRNA and the level of IL-10 were (3.05±1.21)%, 1.36±0.79, 0.21±0.10, (62.82±21.38) ng/L in severe sepsis group; they were (2.86±0.88)%, 1.25±0.56, 0.17±0.08, (56.38±19.65) ng/L in moderate group; they were (2.61±0.87)%, 0.94±0.52, 0.15±0.05, (45.43±14.40) ng/L in mild group. The values showed significant statistical difference among the mild, moderate and severe sepsis groups (all P<0.01). Above values were significantly higher in non-survival group than those in survival group [Treg: (3.46±1.53)% vs. (2.85±1.03)%, t=14.250, P=0.005; miR-155: 1.41±0.85 vs. 1.16±0.76, t=11.875, P=0.006; Foxp3 mRNA: 0.24±0.11 vs. 0.17±0.09, t=8.795,P=0.001; IL-10: 65.47±23.58 ng/L vs. 51.70±16.86 ng/L, t=16.313, P=0.001]. The expression of miR-155 was positively correlated with the expression of CD4(+)CD25(+) Treg and Foxp3 mRNA (r 1=0.635, P 1=0.007; r 2=0.671, P 2=0.005).

The result of this study suggest that miR-155 is involved in the cell proliferation regulation of CD4(+)CD25(+) Treg cells, and play some role in the immunological dissonance in sepsis.